Lapping machine



May/7,1940. H. s. INDGE A2,200,173

LAPPING MACHINE Filed 061'.. 30. 1937 HERBERT SIA/DGE Patented May 7,1940 UNITED STATES PATENT OFFICE LAPPING MACHINE Application October 30,1937, Serial N0. 171,931

8 Claims.

The invention relates to lapping machines, and

with regard to its more specific features to a lapcylinder. Anotherobject of the invention is to provide an attachment whereby shafts canbe quickly lapped. Another object of the invention is to provide anapparatus and method for the efficient lapping of cylindrical bodies.Another object of the invention is to provide a high speed reciprocatingmechanism for the lapping of metal parts involving a minimum ofvibration or stresses set up'by inertia. Other objects will be y in partobvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, arrangements of parts, and in the severalsteps and relation and order of each of said steps to one or more of theothers thereof, all as will be illustratively described herein, and thescope of the application of which will be indicated `1n the followingclaims.

In the accompanyingt drawing in which is illustrated one of manypossible embodiments of the mechanical features of -this invention,

Figure 1 is a front elevation of a grinding machine having the lappingattachment incorporated thereon,

Figure 2 is an enlarged front elevation of the lapping attachmentshowing the wheels and mounting in axial section, and

Figure 3 is a side elevation on the same scale as Figure 2 of thelapping attachment and its mounting on the Wheel head, certain spindlesbeing shown in section.

I provide a plain cylindrical shaft grinder of any preferred or desiredform. Merely for purposes of illustration, I show in Figure 1 acylindrical grinder comprising a base I0 supporting on the usual waysfor longitudinal reciprocation a tableA or carriage II Which carries atone end a headstock I2 and at the otherend a tailstock K I3. Theheadstock journals a spindle, not shown, having on one end thereof adriving face plate I4 and a head center I5. By means ofthe usual lathedog I6, the shaft I1 to be ground is rotated from the face plate I4. Theface plate I4 may be driven by an electric motor 20 having an armatureshaft 2| which drives the spindle for the-face plate by means ofreduction gearing in the head I2, not shown, and a' belt or chain driveinthecasing 2l.

' Tailstock I3 may be of any usual or desiredconstruction, it beingbroken away in Figure 1 more clearly to show the lapping attachment.Both the headstock I2 and the tailstock I3 are adjustable on slideways25 on the table or carriage II in order that the machine may grinddifferent sized shafts I'I.

The machine may have the usual wheel head 30, Figure 3, journalling ashaft 3I upon which is mounted a grinding wheel 32, Figure 1. In suchevent there is preferably provided a motor 33 driving a pulley 34 whichis connected by multiple belts 35 to a pulley 36 attached to the shaft3|.

The usual cross slideways, not shown, for the wheel head 30. are alsoprovided whereby to move the grinding wheel 32 towards and from theShaft I'I.

For control of the cross feed there is provided a hand wheel 40 with amicrometer adjustment device 44I and a ratchet wheel, not shown,operated by a pawl 42 which is attached to a slide 43 operated by aconnecting rod 44 eccentrically attached to a disk 45. Connected to thedisk 45 is a small gear, not shown, which meshesA with a rack on the endof an arm 48 which is connected at 49 to an arm 50 attached to the mainreversing lever 5I which is, positioned for contact with the usual tablereversing dogs or stops 52 and 53 `adjustably secured to thetable orcarriage Il. The reversing lever 5I operates a mechanical reversingmechanism, not shown, to traverse the table II first in one directionand then in the other, according to the position of the lever 5I. Bymeans of a hand lever 55, the direction of travel of `the table I I canbe reversed manually. I provide furthermmanually operated mechanism formoving the table or carriage I I comprising a hand Wheel 60 mounted on ashaft 6I to which is attached a pinion gear 62 meshing with a large gear63 to which is attached a pinion gear 64 meshing with a rack 65 attachedto the under side of the table or carriage II. For the mechanism thusindicated, hydraulic driving and reversing mechanism may be substituted,if desired. For a fuller description of one form of grinding machineembodying many of the features heretofore indicated, reference may bemade to the patent to C. H. Norton No. 762,838 granted June 14, 1904.

Referring now to Figure 3, on the wheel head 30 I provide an extensionI0 having ways receiving a slide 1I which on its under side has a rack12 meshing with a pinion 'I3 controlled by a hand wheel 'I4 whereby theslide' II may be moved parallel to the cross slide of the machine. Iprovide a screw 16 controlled by a hand wheel 11 for locking the slide"II in the desired position of adjustment. The slide 1| supports thelapping attachment which is more particularly the subject matter of thisinvention. As shown in Figures 2 and 3, an electric motor 80'of anyusual or preferred kind is attached to an angle plate 8| which in turnis secured to the slide 1|. The motor has an armature shaft 82 on thefront of which is located a face plate 83 with a vslot 84 in which isadjustably fastened a stud 85 to which is connected a link 86 secured inplace by means of a nut 81. The other end of the link 88 is connected bya pin 88 to levers 89 pivoted on a pin 90 secured to a block 9| attachedb y means of screw bolts 92 to the angle bracket 8|. As shown in Figure3, an upper block 94 and a lower block 95 are held against the anglebracket 8| by means of clamping plates 96 and 91 respectively which areheld in position by bolts 98 and 99. On the under side of the block 94is a V groove |00 and on the upper side of the block 95 is a V groove|00. On each of the upper and lower sides of the block 9| is a V groove|00.

Still referring to Figures 2 and 3, I provide a pair of slides |0| and|02 which have V grooves |03 on their upper and lower surfaces. balls|04 t between the respective grooves4 |00 and |03, as shown in Figure 3.By means of pins |05 and |06 vthe slides |0| and |02 are connected tothe levers 89. Y

It will be seen that as the armature shaft 82 of the motor 80 rotates,the levers 89 will be oscillated and this action will oscillate theslides '|0I and |02. The amplitude of oscillation is such that theslight looseness in the connection at the pins |05 and |06 will takecare of the angular movement of the lever 89 and therefore the slides|0| and I 02 are given a true reciprocating motion. The link 86, thelever 89 and the slides |0| are of skeleton construction as shown,having holes therein clearly illustrated in Figure 2 to remove as muchweight as possible. I have found that it is possible effectively toreciprocate the slides |0| and |02 twelve hundred completereciprocations a minute with an amplitude of about a quarter of an inch.Furthermore, this reciprocation takes place without excessive vibrationof the entire mechanism supported on the slide 1|, since the slides |0|and 02 are always moving oppositely. Friction is reduced to a minimumbymeans of the bearing balls |04 and inertia is reduced toa minimum byremoving as much metal as possible from the various parts, as alreadypointed out.

Still referring to Figure 2, extending from the left hand end of theslides |0| and |02 respectively are integral spindles ||0 upon which aremounted anged sleeves having anges H2 and an interposed washer I3abutting the shoulders |09 which comprise the ends of the slides |0| and|02. 'I'he left hand ends of the sleeves are threaded and by means ofnuts H4 engaging these threaded portions abrasive wheels H5 are securedupon the sleeves |I| to the spindles ||0 having reduced threadedportions ||8 upon Which are nuts ||1 securing the sleeves Il in place.The spindles |I0 have a reduced diame ter cylindrical portion |20extending from the left hand end thereof upon which 4are mounted cups 2|keyed to the, portions |20. The extreme left hand ends of the spindlesH0 are threaded and nuts |22 hold the cups on the portions |20. Insideof the cups |2| are springs |23 exerting vtheir pressure against thecups at one end land against washers |24 at the other end, which washersengage the nuts I4.

Bearing It will thus be seen that the abrasive wheels H5 are thrust tothe right by the springs |23 and the thrust is taken .by the aforesaidshoulders |09.` 'I'his constitutes friction means preventing freerotation of the abrasive wheels ||5.

The abrasive wheels ||5 may be made of any suitable abrasive such asfused aluminaor silicon carbide bonded with any suitable bond such asany one of the clay or resinous bonds, rubber,` or any other type.Furthermore for some purposes diamond abrasive may be used. I have foundthat an excellent finish may be achieved upon a shaft l1 Iby rapidlyreciprocating the wheels ||5 which are held from free rotation asdescribed. 'I'his produces a lapping action upon the work piece whichpeens the grooves produced by grinding. The cups and springs may betermedbraking means to restrain the rotation of the wheels ||5.

In the operation ofthe machine, the operator may rst advance the lcrossslide and grind the shaft l1 in the usual manner. At this time the slide1| will be back so that the abrasive wheels as .by means of the handWheel 60, to Ibring the abrasive wheels H5 opposite the portion of theshaft |1 which was ground. The operator then turns the hand Wheel 14 toadjust the Wheels I I5 into contact with the shaft. In certainembodiments of the invention, the wheels I5 may be 4made of cast iron orthe like and loose abrasive powder may be used to perform the lappingoperation. Forthe lapping a rm contact between the abrasive wheels landthe work piece is preferred but not such a pressure as will materiallyslow down the motor 80. The motor 80 is then energized and operated atan' angular velocity of from six hundred to eighteen hundred R. P. M.

which causes the wheels ||5 to reciprocate at from six to eighteenhundred times a minute, with an amplitude' of any amount up tothreeeighths of an inch. It should be understood that so far as certainfeatures of the invention are concerned, other rates of recipro'cationat other amplitudes may be employed. During the lapping operation, thework piece |1 is rotating in the usual manner, which tends to rotate thewheels H5, but the slight slippage due to the friction against thewheels I I5 materially assists in the lapping action.

It will vthus Ibe seen that there has been provided -by this inventionan apparatus in which 1. A grinding-machine comprising a base, a

table or carriage mounted on said Ibase, a headstock andtailstockrmounted on said carriage, a cross slide, a second slide"mounted on said cross slide, and a lapping attachment on said secondslide comprising a pair of additional slides mounted to reciprocate,means to reciprocate said last named slides, anda small grinding wheelmounted on each of said last named slides.

2. A highI speed lapping attachment comprising a pair of abrasivewheels, spindles mounting said abrasive wheels close together and inparallel relation, said abrasive wheels being free to rotate on saidspindles, means retading the rotaweight slide, a spindle on said slide,a slideway supporting said slide, a grinding wheel mounted to revolve onsaid spindle, means retarding the rotation of said grinding wheel, andmeans to reciprocate said slide rapidly.

4. In apparatus of the class described, a bracket, an electric motormounted on said bracket, a

plate mounted on the armature of said motor, a 'pin radially adjustableon said plate, a link mounted on lsaid pin, a lever to which said linkis connected, a pivot pin on the bracket for the lever, a pair of pinsat equal distances above and below said last named pin, a pair of slidesmounted in parallel relation, each connected to one of said last namedpins, abrasive wheels in coaidal relation mounted on said slides, and,

means to retardthe revolutions of said abrasive wheels.

5. In a grinding machine, means to hold and rotate a generallycylindrical work piece, a grinding wheel to grind said work piece, apair of lapping wheels to lap said work piece mounted on axes parallelto each other and parallel to the grinding Wheel, means to reciprocatesaid lapping wheels oppositely, and means retarding rotation of saidlapping wheels, whereby al1 portions of the work piece may be lapped tothe same extent by grinding and lapping the work piece without removingit from the holding and rotating means.

6. In a machine of the class described, a pair of grinding Wheels, meansmounting said grinding Wheels on parallel axes', means to reciprocatethe grinding wheels axially and oppositely, and means restrainingrotation of the grinding Wheels, whereby to achieve a ilne lappingaction on a work piece.

'7. An attachment comprising a pair of parallel slideways, a pair ofslides mounted in said slideways, bearing balls interposed between theslides and the slideways, reciprocating means for reciprocating theslides oppositely, an abrasive wheel rotatably mounted on each slide,and means to restrain the rotation of each abrasive wheel, whereby toachieve a ne lapping action on a Work piece, the lapping lines .beingbroken up -by the reciprocation.

8. Method of lapping a work piece which is a surface of revolution whichcomprises rapidly reciprocating an abrasive Iwheel in contact with theWork piece, the line of recprocation being parallel to the axis of thework piece, and the abrasive wheel .being rotated by its contact withthe work piece and retarded from free rotation, thus producing adragging actionA on the work piece to effect a fine lapping, thereciprocation breaking up the lapping lines. A

HERBERT S. INDGE.

